Means to arrest and prevent incorrect direction of gear rotation



N v- 1955 E. H. GATES, JR 2,722,297

MEANS TO ARREST AND PREVENT INCORRECT DIRECTION OF GEAR ROTATION Filed Oct. 10, 1951 2 2/ INVENTOR:

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United States Patent MEANS TO ARREST AND PREVENT INCORRECT DIRECTION OF GEAR ROTATION Eugene H. Gates, Jr., Essex, Conn., assignor to The R. W. Cramer Company, Incorporated, Centerbrook, Conn., a corporation of Connecticut Application October 10, 1951, Serial No. 250,755

22 Claims. (Cl. 1924) This invention is a novel means to arrest and prevent incorrect direction of gear rotation, that is, as to any given gear of a train, oppositely to a predetermined or preselected correct rotary direction thereof. A typical device of this known class comprises an arresting element cooperative with a train of meshed gears, such as a pair, referred to as first and second gears, which may be part of a more extensive drivable train. An illustrative special example is that of a self-starting synchronous motor wherein the starting rotation, say of the first gear of the pair, is unpredictable or non-predeterminable in the direction, and it is required to preclude the wrong or incorrect starting, as by a device acting directly or indirectly upon the first gear, or upon its teeth, such as spur teeth.

Numerous other instances may be recited of the general principles of the present invention to be disclosed, apart from the specific illustration hereof. Among other uses are some cases requiring the principles of a free-wheeling or one-way clutch, as for chain hoists, winches, stem winding clocks, and the like.

A known and marketed form of motor having one kind of arresting device is that shown in E. L. Schellens Patent No. 2,436,231 granted February 17, 1948, which requires the complication of a certain cutaway form of recessed teeth involving undue manufacturing drawbacks and costs. In any such example the arresting may prevent, as in clock mechanism, the occurrence of the erroneous direction of starting rotation; and at the same time, if desired, by utilizing impact and rebound, the first gear may be forthwith reversed and set into the correct direction, and the clock or other train thus caused to assume the correct normal running direction.

An object hereof is to promote simplicity of structure and operation, and to afford efficiency and durability, as will be further explained. Thus, when incorrect rotation starts, the whole apparatus may be brought to an immediate full stop; or it may be arrested and promptly restarted correctly, as a clock requires.

A further object is to provide the preexisting clock or other apparatus with operative means, according to this invention, which is small and compact and thus adapted to be accommodated in a small available space adjacent to the preexisting or supplied train of gears.

Another object is to provide a device to arrest and prevent incorrect direction of gear rotation without the need of making any basic change in the gearing itself but by the mere supplementing of the gearing by the addition of a special arresting device according to the principles hereof. In other words conventional gears may be used.

Further objects and advantages of the invention will be explained in the hereinafter following description of an illustrative example of the invention or will be understood by those conversant with the subject. To the attainment of such objects and advantages the present invention consists in the novel device and the novel features of structure, combination and operation hereinafter illustrated or disclosed.

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In the accompanying drawings, Fig. 1 is a partial top plan view of an illustrative motor, such as a self-starting synchronous motor, as of the type shown in said prior patent, with the present invention embodied therein; the parts being shown in their normal freerunning condition, in the correct direction, corresponding with Fig. 2.

Figs. 2 and 3 are diagrammatic, both showing in top view the essential parts and principles of the invention, irrespective of their embodiment in any particular apparatus or mechanism; Fig. 2 representing either the normal free-running of the mechanism in the desired rotary direction, with the arresting means retracted and inoperative; or a fortuitous run-down or idle position of the parts after all operation has ceased.

Fig. 3 in the same top view shows the same parts as shown in Fig. 2 but in their blocked or obstructed position, the obstructing piece or spur having entered the space between two adjacent teeth of one of the meshing or mating gears, so as to be in contact with both or at least one of such teeth, with arresting of rotation as shown; and if the mechanism be constructed to provide rebound of the parts, with correction of direction, Fig. 3 may be considered as showing the arresting position of the parts at the instant before such rebound.

Fig. 4, looking from the front, is a vertical sectional view of the mechanism and parts in the position of Fig. 2, taken on the section line 44 of Fig. 2.

To the attainment of the recited objects and advantages the present invention or mechanism to be described comprises, in one aspect, a means or device to arrest and prevent the incorrect one of the two possible directions of gear rotation, in which mechanism are combined the following elements: a pair of toothed gears (20, 21) in meshing engagement a separate obstructor or blocking member (30) freely shiftable between an advanced obstructing position Fig. 3) engaging one or more teeth of, and thereby blocking, a first one (20) of said gears, and a retracted or normally idle position (Fig. 2) disengaging and releasing said first gear; shifting means (21, 31) operated from or by the rotation of another or second one (21) of said gears for advancing the obstructing member (30) into its blocking position when said gear is turning or has been started in an incorrect direction; and said mechanism having parts (as teeth 23 or parts 21, 31) operative to return or retract the obstructing member (30) when the gear is turning or has been started in the correct direction, thereby to render idle the obstructor and to permit the respective gears to turn freely in their correct direction of rotation. The mechanism preferably comprises also a stop means (33, 34) adapted to bring the obstructor to rest in each retracting shift in an idle normal position disengaged from but adjacent to its active blocking position. Preferably also the shifting of the obstructing member is a short arcuate oscillation about the axis of said second gear (21); and preferably the actuating or obstructor shifting means comprises a frictional contact arrangemetn between a part or face of the second gear and the body or disk part (31) of the obstructing member. When the invention is embodied in a self-starting motor-driven clockwork the parts are advantageously arranged and related to deliver an impact, with a rebounding kick when the direction is wrong, thus to restart instantaneously and correctly the clockwork for normal operation.

More concisely the gear mechanism hereof comprises gears in train, together with an obstructor freely oscillatable between an advanced position engaging a first one of said gears to obstruct it against rotation in an erroneous direction and a retracted position disengaging and releasing said first gear for free rotation in the correct direction; actuating means operated by the rotation of a second one of said gears for advancing the obstructor into its obstructing position Whenever said second gear turns in the erroneous direction; and means to cause retraction of the obstructor Whenever said gear turns in the correct direction thereby to release and permit said gears to turn freely each in its correct direction.

Referring to the illustrated mechanism, Fig. 1 shows an example of the invention embodied in a self-starting synchronous motor, as of the induction type, already hereinabove described to some extent. Fig. 1 in top plan view shows a portion of an actual embodiment of such a motor with the present invention utilized therein; whereas the remaining figures, on a larger scale, show the principles of the invention in a more or less diagrammatic way. Certain conventional general motor parts appear in Fig. 1 only and will first be referred to. While the motor may be enclosed Within outer walls of various shapes, for various purposes, a generally cylindrical casing wall is shown, which serves conventionally also as a part of the motor frame.

Contained within the casing are shown various elements, of which the following are considered suflicient to describe. The stator of such a motor is of fixed character and it is shown as comprising an outer pole ring 11 from which project inwardly a circumferential series of outer poles 12. These elements cooperate magnetically with an inner pole ring 13 carrying an inner series of poles 14, these latter poles extending upwardly to where their terminals are at the same level as and alternated with the terminals of the outer poles 12. One of the poles 15 of the inner series is selected to constitute a stop for an element 33 which will be explained in further detail in connection with Figs. 2 to 4 wherein is shown a fixed stop 34 with which the stop 15 corresponds. Cooperating with the elements 11 to 14 is the rotor member 16 of the motor, this being largely broken away the better to shown other parts of the motor. The rotor 16 is shown of the type comprising a rotary disk, the outer edge of which is deeply scalloped to form a series of peripheral rotor poles 17. The above described stator and rotor elements correspond largely with those shown in prior Patent No. 2,436,231 hereinabove identified, said patent showing also an elevational view of the interior mechanism of the type of motor wherein the present invention has been illustrativeiy embodied.

Certain general elements of the disclosure are contained in Fig. l and in Figs. 2 to 4, including the rotor shaft 19, which is preferably the same shaft that carries what for identification is herein termed the first gear 20, fast or loose on the shaft. This shaft and the gear are well shown in top view in Figs. 2 and 3, in different positions; and to the left thereof are shown a counter shaft 19 and a counter gear 20 merely as illustrations of how the present invention can be utilized for gear trains of various types and uses.

The gear train including the aforesaid first gear 20 includes also what is termed, for definition, the second gear 21, this gear pair being in constant mesh and associated with the main gear train, the second being considered the mating gear for the first of this pair. The gear 20 is preferably fast upon the upright shaft 19, which may carry other gears or pinions having to do with the motor or other mechanism or with the speed reduction train thereof. The first and second gears respectively may be considered the driving and driven gears of the mechanism, the first receiving its drive in any manner as from the electric motor described; and the second gear may be intermediate between the first gear and others beyond either or both of the two gears, although the second gear may desirably be provided solely as an offset gear to mesh with the first gear, without constituting an intermediate gear of a train; and the drawings so illustrate this arrangement. Both of the gear pair may be entirely conventional, as shown, without need of the mutilation or special design of gear teeth as shown in said prior patent.

While the second gear 21 may be fast to a supporting shaft, it is herein shown as being mounted upon and surrounding an upright axle 22, with preferably a bushing or lining interposed between axle and gear, as will be further described. The axle may be like a fixed upright stud giving support to the bushing and through it to the second gear and to the blocking or obstructing member 30 to be described. For convenience the teeth of the gear pair are designated as 23 for the first gear and 24 for the second gear, these in certain aspects being distinct elements from the bodies or webs of these gears. The frame on which the first and second gears are mounted, by shaft 19 and axle 22, comprises a horizontal plate 26, carrying bearing means for the gears and obstructor and serving for the upright support of the axle 22.

While the gear 21 and obstructor 30 might be arranged for rotation directly on the fixed axle 22 by means of shoulders thereon it is preferred to provide a conventional bushing 27, which surrounds and may rotate on the axle, constituting a lining ring for the rotation of the surrounding elements 21 and 30. It is preferable that the surrounding elements may turn freely on the bushing and the bushing turn freely on the axle, so as to render the mechanism as light-running as possible. The bushing 27 is shown of a usual form, with its top flange 29 and its depending sleeve 28. The sleeve may be sufliciently tall to rest upon the base 26, thus holding the bushing in place, with its top flange sufficiently high to avoid applying the weight of the bushing to the elements 30 and 21 therebelow; or the sleeve may be shorter so that the flange may bear frictionally upon the obstructor. The preferred arrangement in these particulars is best shown in Fig. 4, wherein the second gear 21 is of less thickness than the first gear 20, it surrounding the sleeve or shank of the bushing which in turn surrounds and has rotary bearing with the interior axle 22. The obstructor 3t) overlies the gear 21, the two being placed in actual direct contact to afford an operative degree of friction between them, being a preferred mode of transmitting oscillation to the obstructor. As shown, the axle 22 stands up somewhat above the top flange 29 of the bushing, which may be sufiicient when the motor is used in a horizontal position; otherwise the axle might carry a cap at its upper end confining the elements 21, 27 and 30 against displacement.

The obstructor 30, already incidentally referred to, is shown as a single or one-piece blocking member mounted to shift or oscillate in its operation, and formed with a disk-like or flat body 31, which may be mounted on and swing to and fro about the fixed axle 22, and bushing 27, adjacent to and contacting, face to face, or with slip connection, the second gear 21. Through said connection, shown frictional, the advancing shift or swing of the obstructor is brought about; the obstructor body carrying a peripherally projecting spur or finger piece 32, which performs the blocking of the first gear 20. The frictional connection between the bodies or disks of gear 21 and obstructor 3t) afford an operative shifting or slip engagement adapted to serve both to advance the obstructor and spur to blocking position, and to retract these to idle position.

For their mutual contact the gear may surround the axle 22, or its bushing 27, with a running fit. If the axle be upright the gear may be fitted to surround the bushing and rest down upon a shoulder or frame part 26 below; and for their mutual contact the obstructor may rest down upon the gear, thus affording the frictional drive between the two while leaving them independently movable, with a slip fit. The gear and the obstructor may have similar central holes fitting upon the bushing sleeve, thus providing a compact assembly of gear, obstructor and bushing, all mounted upon the axle which may stand upright fixedly above the frame piece 26. The obstructor overlies the gear and underlies the top flange of the bushing, which latter while confining the parts below, exerts no undue restraint upon the obstructor, and may even have minute clearance; so that the rotation of the gear can frictionally operate on the obstructor to cause the advancing swing of the latter when the gears turn in the erroneous direction, as already described, thus shifting the obstructor from its idle position of Fig. 2 to its blocking position of Fig. 3; with a reversed slip action for retraction to idle position.

If the obstructor should meet the teeth of the first gear with such impact as to cause a rebound, that action tends to unblock the first gear while causing retracting oscillation of the obstructor, to pass from the Fig. 3 to the Fig. 2 position, and leaving the gears completely free for normal rotation. In these aspects the teeth 23 of the first gear may be considered a means to initiate the retracting swing of the obstructor; this being supplemental to the friction action which is constantly in efiect between the second gear and the obstructor, the correct rotation of the second gear then inducing the retraction of the obstructor to its idle position.

Instead of leaving the retracting swing of the obstructor to come to rest by chance, giving variable action of the device, a stop means is provided, standing always ready to terminate the retractive swing of the obstructor; by which means the extent of retraction may be governed, for example to bring it to rest in the idle position shown in Fig. 2, with safe clearance between the obstructor spur 32 and the teeth 23 of the first gear.

While various types of stop device may be used, an effective arrangement is shown in the form of a projecting arm, lug or bar 33 extending for example radially from 'the body of the obstructor, and this cooperating with a fixed main stop or contact member 34. Thus in Fig. 2 the retraction has proceeded to the extent that the swinging contact arm 33 of the stop has met the fixed contact post 34. When the action is reversed, due to erroneous direction of rotation, no opposing stop is required, since the entry of the spur 32 within a tooth space of the first gear, or in blocking contact with a tooth thereof, constitutes suflicient stoppage for the advancing swing of the obstructor.

The main stop 34 is shown as a simple post upstanding from the base 26, and it may be adjustable in position but preferably stops the retraction of the obstructor in a position with its spur close to the obstructing position thereof.

Figs. 2 and 3 show in addition to the main stop or post 34 a secondary such stop 35, at the opposite side of the obstructor contact arm 33. This auxiliary stop does not function during normal operation of the mechanism; but this element presents a convenience when changes are made in the position or posture of an electric motor, in that, by having an opposite pair of fixed contacts, the device of this invention will permit ready reversal of the action of the system, and of the matter of direction of rotation, by the mere removal, inversion and replacement of the obstructors 36-3132.

In operation, with the mechanism set as shown in Fig. 2, the first and second gears, which may be always in mesh, normally turn freely in corresponding but opposite rotary directions, the first gear counterclockwise, the second gear 21 clockwise. The separate blocking member, or oscillating blocker 30, with its spur or pawl 32, and as well the coaxial gear 21, have free running fit, preferably on the optional bushing 27, which turns freely on the fixed axle 22. The bushing top flange 29 may be clear of, but preferably bears lightly on, the blocker or obstructor, which latter is therefore confined between said flange and gear 21, which frictional engagement at one or both faces of the blocker, by which the rotation of gear 21 provides the force to turn or swing the blocker at certain times, with retraction as in Fig. 2 and advance as in Fig. 3. This frictional actuation of the blocker is adequate for each purpose; the advance being terminated by the engagement of the spur with the gear 20, and the retraction by the blocker arm engaging the fixed stop 34.

The resting or poising of the retracted blocker, with its spur very close to its advanced blocking position, permits instantaneous stoppage, within the interval of one tooth space, predetermined by the relative positioning of the blocker arm and the fixed stop. By proper positioning of the stop contacts and the relation of the blocker spur to the first gear, an effective and reliable starting may be ensured, sometimes of high practical importance.

In the absence of impact and rebound, the blocker when in the Fig. 3 position will remain there with all parts at rest, awaiting some influence to restart the mechanism, as by swinging the blocker arm or handle 33 retractingly into contact with the stop 34, following which the gears will run freely in the directions indicated by the direction arrows in Fig. 2. If there be rebound this automatically causes restoration of normal free running of the gears, as described.

There has thus been illustrated and described a means to arrest and prevent incorrect direction of gear rotation embodying the principles and attaining the advantages of the present invention; and since various matters of structure, combination and operation may be variously modified without departing from such principles it is not intended to limit the invention thereto except to the extent set forth in the appended claims.

What is claimed is:

1. In a gear mechanism having means to arrest and prevent the incorrect one of two possible directions of gear rotation, the combination of a gear train including at least a pair of toothed gear in continuously mutually meshing engagement; a separate obstructor or blocking member mounted to be freely shiftable in an arcuate path between and advanced obstructing position engaging one or more teeth of and thereby blocking a first one of said gears, and a retracted or normally idle position disengaging and releasing said first gear, frictional shifting means operated from or by the rotation of a second one of said gears for advancing the obstructor into its obstructing position when said second gear is turning or has been started in the incorrect direction; and means comprised in said mechanism operative to retract the obstructor whenever said second gear turns or has been started in the correct direction, thereby to render idle the obstructor and to permit the gears respectively to turn freely each in its correct direction of rotation; and the said arcuate path of said blocking member being coaxial with said second gear.

2. The combination as in claim 1 and wherein the shifting of the obstructor is a short oscillation of advance and retraction in an arcuate path coaxial with the rotation of the second gear; and such oscillation, at least during advance, is brought about by frictional contact engagement between a side surface of the second gear and the surface of the body or disk of the obstructor.

3. The combination as in claim 1 and wherein is stop means arranged to limit the extent of each retraction of the obstructor to a retracted idle position spaced from but adjacent to its advanced position, thereby to afford quick arresting of erroneous rotation of the gears.

4. In a synchronous self-starting motor having an indeterminate direction of starting rotation, the combination as in claim 1 and wherein the obstructor is advanced to its obstructing position, in the case of erroneous direction of rotation, with impact upon teeth of the first gear and rebound therefrom, thereby reversing instantaneously the gears to their correct direction of rotation, the teeth of the first gear thereupon acting to reverse the obstructor into retracting shift to idle position, leaving the gears to rotate freely in the correct direction.

5. The combination as in claim 1 and wherein the shifting means consists of the mutually contacting faces of the second gear and obstructor providing a frictional connection operative to swing the obstructor to blocking position when said gear starts or turns in the wrong direction and to idle position when said gear turns in the correct direction.

6. The combination as in claim 1 and wherein the obstructor has a disk-like body contiguous to the second gear, with an obstructing spur or finger-piece projecting from the body and adapted to enter a tooth space of the first gear when advanced, and a mounting hole permitting oscillation alongside the rotation of the second gear.

7. The combination as in claim 1 and wherein the obstructor is mounted coaxially with the second gear to receive a short swing between blocking and idle posi' tions, with a loose operating connection, working by friction, from the second gear to the obstructor body.

8. In a combination as in claim 7, wherein the coaxial second gear and the obstructor are in frictional contact but freely relatively shiftable, a mounting arrangement comprising a fixed stud on the frame, a sleeved bushing on the stud, the second gear being rotatable on the bushing sleeve, the obstructor being rotatable on said sleeve and resting in contact on the gear, and the bushing having a top flange overlying the obstructor and hold ing it and the gear in place.

9. In combination with a gear train including a meshing pair of rotary gears, an obstructor mounted for free oscillation between an advanced position engaging and obstructing a first one of said pair of gears against rotation in an erroneous direction and an idle retracted position disengaged from and releasing said first gear for free rotation in the correct direction; said obstructor having a blocking spur or finger at the periphery of its body adapted when advanced to enter a tooth space of said first gear for blocking the same; and frictional shifting means operated by the rotation of a second one of said gears for advancing the obstructor into its obstructing position whenever said second gear turns in the erroneous direction; said obstructor being mounted coaxially of the second gear, and said shifting means consisting of the contacting bodies of obstructor and gear affording a slip connection with frictional shifting of the obstructor.

10. The combination as in claim 9 and wherein is means, as said teeth of the first gear, to retract the obstructor to idle position whenever the first gear turns in the correct direction.

11. The combination as in claim 9 and wherein is means, as said frictional shifting means, to retract the obstructor to idle position whenever the first gear turns in the correct direction.

12. The combination as in claim 9 and wherein is retracting means for the obstructor, operative whenever the gears turn in their correct directions, together with a stop means to limit the retraction of the obstructor to an idle position allowing a small clearance from its blocking.

13. The combination as in claim 9 and wherein is retracting means for the obstructor, operative whenever the gears turn in their correct directions, together with a stop means to limit the retraction of the obstructor to an idle position allowing a small clearance from its blocking, and means to adjust the stop means to predetermine the extent of clearance between the first gear and the obstructor.

14. In combination with a gear train including a meshing pair of rotary gears, an obstructor mounted for free oscillation between an advanced position engaging and obstructing the first one of said pair of gears against rotation in an erroneous direction and an idle retracted position disengaged from and releasing said first gear for free rotation in the correct direction; said obstructor being fitted to swing coaxially of the second gear and having a blocking spur adapted when advanced to engage a tooth or teeth of said first gear for blocking said gear; a drag or slip action shifting means operated by the rotation of the second gear for advancing the obstructor into its obstructing position whenever said second gear turns in the erroneous direction; said drag means being adapted to retract the obstructor from its drag engagement with the first gear whenever the second gear turns in the correct direction, thereby to render idle the obstructor and re lease the gears for free-running; and stop means positioned to determine and limit the extent of retraction of the obstructor and its position of rest.

15. The combination as in claim 14 and wherein the stop means comprises a projecting arm or contact reaching outward radially of the obstructor and oscillating with it, and co-operating therewith a fixed contact or post standing in the path of the oscillating obstructor arm.

16. In a self-starting synchronous electric motor a gear mechanism having a gear pair, a retractible separate obstructor, and a frictional advancing means for the obstructor, all as in claim 10 recited; together wtih a stop means to limit the retraction of the obstructor to an idle position allowing a small clearance from its blocking position.

17. An electric motor as in claim 16 and wherein are cooperating stator and rotor poles, and the stop means consists of a stator fixed pole located in the retracting path of oscillation of the obstructor.

18. In combination with a gear train including a meshing pair of rotary gears, an obstructor mounted for free oscillation between an advanced position engaging and obstructing a first one of said pair of gears against rotation in an erroneous direction and an idle retracted position disengaged from and releasing said first gear for free rotation in the correct direction; said obstructor having a blocking spur or finger at the periphery of its body adapted when advanced to enter a tooth space of said first gear for blocking the same; means for causing the advancing and retracting shiftings of the obstructor, including a frictional shifting means operated by the rotation of a second one of said gears for advancing the obstructor into its obstructing position whenever said second gear turns in the erroneous direction; said obstructor being mounted coaxially of the second gear, and said shifting means consisting of the contacitng bodies of obstructor and gear aifording a slip connection with fric tional shifting of the obstructor; and stop means positioned in relation to the obstructor to limit each retraction thereof to leave it clear of but closely adjacent to the teeth of the first gear.

19. In combination with a gear train including a continuously meshing pair of gears, an obstructor freely oscillatable between an advanced position engaging a first one of said gears to obstruct it against rotation in an erroneous direction and a retracted position disengaging and releasing said first gear for free rotation in the correct direction, an obstructor-actuating means and a cooperating friction means through which said actuating means is actuated by the rotation of a second one of said gears for advancing the obstructor into its obstructing position whenever said second gear turns or starts in the erroneous direction; said obstructor arranged :to swing coaxially with the rotation of the second gear; and means to cause retraction of the obstructor whenever .said gear starts or turns in the correct direction thereby to release and permit said gears to turn freely each in its correct direction; the obstructor and vsecond gear surfaces being arranged in mutual rubbing contact thereby to maintain a frictional or slip drive actuation between :said second gear and the obstructor.

2G. The combination as in claim 19 and wherein the shifting of the obstructor is a short oscillation of advance and retraction in an arcuate path, and such oscillation, during its advance and retractive shiftings, jis :frictionally eiiected by engaging contact between aface of :the second gear and the contiguous surface or body of the obstructor.

21. The combination as in claim 19 and wherein is a stop arranged to limit the extent of each swinging retraction of the obstructor, to a retracted idle position wherein it is spaced from but adjacent to its advanced position, thereby to afford quick arresting of the erroneous rotation of the gears.

22. In a gear mechanism, in combination, a gear train including mutually meshed first and second gears; a separate blocker mounted to advance and retract in an oscillating manner and coaxially with the second gear by an operating means acting between said second gear and blocker, namely, from a normally idle position to an advanced position blocking the first gear by engaging the teeth thereof, and to retract to such idle position, thereby References Cited in the file of this patent UNITED STATES PATENTS 1,671,739 Paca May 29, 1928 1,697,333 Turnbull Jan. 1, 1929 1,849,301 Johnston Mar. 15, 1932 2,090,357 Regan Aug. 17, 1937 

